William David Blakeslee Ainey (April 8, 1864 – September 4, 1932) was a Republican member of the U.S. House of Representatives from Pennsylvania.

Ainey was elected as a Republican to the 62nd United States Congress to fill the vacancy caused by the death of George W. Kipp.

He served as secretary and president of the Japanese-American group of inter-parliamentarians and delegate in 1914 to Tokyo, Japan, and to Stockholm, Sweden.

He was appointed a member of the Public Service Commission of Pennsylvania on May 20, 1915, and on August 20, 1915, was elected chairman.

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